diff options
Diffstat (limited to 'drivers/reset/core.c')
-rw-r--r-- | drivers/reset/core.c | 217 |
1 files changed, 123 insertions, 94 deletions
diff --git a/drivers/reset/core.c b/drivers/reset/core.c index f15f150b79da..72b32bd15549 100644 --- a/drivers/reset/core.c +++ b/drivers/reset/core.c @@ -8,6 +8,7 @@ * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. */ +#include <linux/atomic.h> #include <linux/device.h> #include <linux/err.h> #include <linux/export.h> @@ -18,19 +19,27 @@ #include <linux/reset-controller.h> #include <linux/slab.h> -static DEFINE_MUTEX(reset_controller_list_mutex); +static DEFINE_MUTEX(reset_list_mutex); static LIST_HEAD(reset_controller_list); /** * struct reset_control - a reset control * @rcdev: a pointer to the reset controller device * this reset control belongs to + * @list: list entry for the rcdev's reset controller list * @id: ID of the reset controller in the reset * controller device + * @refcnt: Number of gets of this reset_control + * @shared: Is this a shared (1), or an exclusive (0) reset_control? + * @deassert_cnt: Number of times this reset line has been deasserted */ struct reset_control { struct reset_controller_dev *rcdev; + struct list_head list; unsigned int id; + unsigned int refcnt; + int shared; + atomic_t deassert_count; }; /** @@ -62,9 +71,11 @@ int reset_controller_register(struct reset_controller_dev *rcdev) rcdev->of_xlate = of_reset_simple_xlate; } - mutex_lock(&reset_controller_list_mutex); + INIT_LIST_HEAD(&rcdev->reset_control_head); + + mutex_lock(&reset_list_mutex); list_add(&rcdev->list, &reset_controller_list); - mutex_unlock(&reset_controller_list_mutex); + mutex_unlock(&reset_list_mutex); return 0; } @@ -76,18 +87,23 @@ EXPORT_SYMBOL_GPL(reset_controller_register); */ void reset_controller_unregister(struct reset_controller_dev *rcdev) { - mutex_lock(&reset_controller_list_mutex); + mutex_lock(&reset_list_mutex); list_del(&rcdev->list); - mutex_unlock(&reset_controller_list_mutex); + mutex_unlock(&reset_list_mutex); } EXPORT_SYMBOL_GPL(reset_controller_unregister); /** * reset_control_reset - reset the controlled device * @rstc: reset controller + * + * Calling this on a shared reset controller is an error. */ int reset_control_reset(struct reset_control *rstc) { + if (WARN_ON(rstc->shared)) + return -EINVAL; + if (rstc->rcdev->ops->reset) return rstc->rcdev->ops->reset(rstc->rcdev, rstc->id); @@ -98,26 +114,48 @@ EXPORT_SYMBOL_GPL(reset_control_reset); /** * reset_control_assert - asserts the reset line * @rstc: reset controller + * + * Calling this on an exclusive reset controller guarantees that the reset + * will be asserted. When called on a shared reset controller the line may + * still be deasserted, as long as other users keep it so. + * + * For shared reset controls a driver cannot expect the hw's registers and + * internal state to be reset, but must be prepared for this to happen. */ int reset_control_assert(struct reset_control *rstc) { - if (rstc->rcdev->ops->assert) - return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id); + if (!rstc->rcdev->ops->assert) + return -ENOTSUPP; - return -ENOTSUPP; + if (rstc->shared) { + if (WARN_ON(atomic_read(&rstc->deassert_count) == 0)) + return -EINVAL; + + if (atomic_dec_return(&rstc->deassert_count) != 0) + return 0; + } + + return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id); } EXPORT_SYMBOL_GPL(reset_control_assert); /** * reset_control_deassert - deasserts the reset line * @rstc: reset controller + * + * After calling this function, the reset is guaranteed to be deasserted. */ int reset_control_deassert(struct reset_control *rstc) { - if (rstc->rcdev->ops->deassert) - return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id); + if (!rstc->rcdev->ops->deassert) + return -ENOTSUPP; - return -ENOTSUPP; + if (rstc->shared) { + if (atomic_inc_return(&rstc->deassert_count) != 1) + return 0; + } + + return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id); } EXPORT_SYMBOL_GPL(reset_control_deassert); @@ -136,18 +174,54 @@ int reset_control_status(struct reset_control *rstc) } EXPORT_SYMBOL_GPL(reset_control_status); -/** - * of_reset_control_get_by_index - Lookup and obtain a reference to a reset - * controller by index. - * @node: device to be reset by the controller - * @index: index of the reset controller - * - * This is to be used to perform a list of resets for a device or power domain - * in whatever order. Returns a struct reset_control or IS_ERR() condition - * containing errno. - */ -struct reset_control *of_reset_control_get_by_index(struct device_node *node, - int index) +static struct reset_control *__reset_control_get( + struct reset_controller_dev *rcdev, + unsigned int index, int shared) +{ + struct reset_control *rstc; + + lockdep_assert_held(&reset_list_mutex); + + list_for_each_entry(rstc, &rcdev->reset_control_head, list) { + if (rstc->id == index) { + if (WARN_ON(!rstc->shared || !shared)) + return ERR_PTR(-EBUSY); + + rstc->refcnt++; + return rstc; + } + } + + rstc = kzalloc(sizeof(*rstc), GFP_KERNEL); + if (!rstc) + return ERR_PTR(-ENOMEM); + + try_module_get(rcdev->owner); + + rstc->rcdev = rcdev; + list_add(&rstc->list, &rcdev->reset_control_head); + rstc->id = index; + rstc->refcnt = 1; + rstc->shared = shared; + + return rstc; +} + +static void __reset_control_put(struct reset_control *rstc) +{ + lockdep_assert_held(&reset_list_mutex); + + if (--rstc->refcnt) + return; + + module_put(rstc->rcdev->owner); + + list_del(&rstc->list); + kfree(rstc); +} + +struct reset_control *__of_reset_control_get(struct device_node *node, + const char *id, int index, int shared) { struct reset_control *rstc; struct reset_controller_dev *r, *rcdev; @@ -155,12 +229,22 @@ struct reset_control *of_reset_control_get_by_index(struct device_node *node, int rstc_id; int ret; + if (!node) + return ERR_PTR(-EINVAL); + + if (id) { + index = of_property_match_string(node, + "reset-names", id); + if (index < 0) + return ERR_PTR(-ENOENT); + } + ret = of_parse_phandle_with_args(node, "resets", "#reset-cells", index, &args); if (ret) return ERR_PTR(ret); - mutex_lock(&reset_controller_list_mutex); + mutex_lock(&reset_list_mutex); rcdev = NULL; list_for_each_entry(r, &reset_controller_list, list) { if (args.np == r->of_node) { @@ -171,78 +255,29 @@ struct reset_control *of_reset_control_get_by_index(struct device_node *node, of_node_put(args.np); if (!rcdev) { - mutex_unlock(&reset_controller_list_mutex); + mutex_unlock(&reset_list_mutex); return ERR_PTR(-EPROBE_DEFER); } if (WARN_ON(args.args_count != rcdev->of_reset_n_cells)) { - mutex_unlock(&reset_controller_list_mutex); + mutex_unlock(&reset_list_mutex); return ERR_PTR(-EINVAL); } rstc_id = rcdev->of_xlate(rcdev, &args); if (rstc_id < 0) { - mutex_unlock(&reset_controller_list_mutex); + mutex_unlock(&reset_list_mutex); return ERR_PTR(rstc_id); } - try_module_get(rcdev->owner); - mutex_unlock(&reset_controller_list_mutex); - - rstc = kzalloc(sizeof(*rstc), GFP_KERNEL); - if (!rstc) { - module_put(rcdev->owner); - return ERR_PTR(-ENOMEM); - } + /* reset_list_mutex also protects the rcdev's reset_control list */ + rstc = __reset_control_get(rcdev, rstc_id, shared); - rstc->rcdev = rcdev; - rstc->id = rstc_id; + mutex_unlock(&reset_list_mutex); return rstc; } -EXPORT_SYMBOL_GPL(of_reset_control_get_by_index); - -/** - * of_reset_control_get - Lookup and obtain a reference to a reset controller. - * @node: device to be reset by the controller - * @id: reset line name - * - * Returns a struct reset_control or IS_ERR() condition containing errno. - * - * Use of id names is optional. - */ -struct reset_control *of_reset_control_get(struct device_node *node, - const char *id) -{ - int index = 0; - - if (id) { - index = of_property_match_string(node, - "reset-names", id); - if (index < 0) - return ERR_PTR(-ENOENT); - } - return of_reset_control_get_by_index(node, index); -} -EXPORT_SYMBOL_GPL(of_reset_control_get); - -/** - * reset_control_get - Lookup and obtain a reference to a reset controller. - * @dev: device to be reset by the controller - * @id: reset line name - * - * Returns a struct reset_control or IS_ERR() condition containing errno. - * - * Use of id names is optional. - */ -struct reset_control *reset_control_get(struct device *dev, const char *id) -{ - if (!dev) - return ERR_PTR(-EINVAL); - - return of_reset_control_get(dev->of_node, id); -} -EXPORT_SYMBOL_GPL(reset_control_get); +EXPORT_SYMBOL_GPL(__of_reset_control_get); /** * reset_control_put - free the reset controller @@ -254,8 +289,9 @@ void reset_control_put(struct reset_control *rstc) if (IS_ERR(rstc)) return; - module_put(rstc->rcdev->owner); - kfree(rstc); + mutex_lock(&reset_list_mutex); + __reset_control_put(rstc); + mutex_unlock(&reset_list_mutex); } EXPORT_SYMBOL_GPL(reset_control_put); @@ -264,16 +300,8 @@ static void devm_reset_control_release(struct device *dev, void *res) reset_control_put(*(struct reset_control **)res); } -/** - * devm_reset_control_get - resource managed reset_control_get() - * @dev: device to be reset by the controller - * @id: reset line name - * - * Managed reset_control_get(). For reset controllers returned from this - * function, reset_control_put() is called automatically on driver detach. - * See reset_control_get() for more information. - */ -struct reset_control *devm_reset_control_get(struct device *dev, const char *id) +struct reset_control *__devm_reset_control_get(struct device *dev, + const char *id, int index, int shared) { struct reset_control **ptr, *rstc; @@ -282,7 +310,8 @@ struct reset_control *devm_reset_control_get(struct device *dev, const char *id) if (!ptr) return ERR_PTR(-ENOMEM); - rstc = reset_control_get(dev, id); + rstc = __of_reset_control_get(dev ? dev->of_node : NULL, + id, index, shared); if (!IS_ERR(rstc)) { *ptr = rstc; devres_add(dev, ptr); @@ -292,7 +321,7 @@ struct reset_control *devm_reset_control_get(struct device *dev, const char *id) return rstc; } -EXPORT_SYMBOL_GPL(devm_reset_control_get); +EXPORT_SYMBOL_GPL(__devm_reset_control_get); /** * device_reset - find reset controller associated with the device |